I am a sophomore and play the Baritone in the SCHS (go wild cats!) marching band. I have been in band for four years. I honestly didn't do band originally for anything other than it would look good on a college résumé, but we are currently working on Pandora Reopened for our marching band show. We won at our first competition and the show is awesome.
My problem is that, up until now since I did not actually care about band, I did not put the effort into learning anything but the basics of my instrument. A major problem that is stumping me is how to interpret the key signature. I generally know what to do, but I do not know official terms for much.
My question:
Does the key signature affect which notes I will play? For example, does a B-flat key signature simply indicate that all notes I play are flat. This is how I have interpreted it up until now. I know that it is my responsibility to learn this, because it is my screw up, but I cannot find a good description in simple terms. Can someone give me a very brief description on how to understand the basic concepts of the key signature?